EP2647059A1 - A new electrical conductor for attaching silicon wafers in photovoltaic modules - Google Patents
A new electrical conductor for attaching silicon wafers in photovoltaic modulesInfo
- Publication number
- EP2647059A1 EP2647059A1 EP10782319.7A EP10782319A EP2647059A1 EP 2647059 A1 EP2647059 A1 EP 2647059A1 EP 10782319 A EP10782319 A EP 10782319A EP 2647059 A1 EP2647059 A1 EP 2647059A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- electrical conductor
- copper
- copper material
- silicon wafer
- conductor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000004020 conductor Substances 0.000 title claims abstract description 77
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 50
- 239000010703 silicon Substances 0.000 title claims abstract description 50
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 48
- 235000012431 wafers Nutrition 0.000 title abstract description 46
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 94
- 229910052802 copper Inorganic materials 0.000 claims abstract description 94
- 239000010949 copper Substances 0.000 claims abstract description 94
- 239000000463 material Substances 0.000 claims abstract description 81
- 238000000034 method Methods 0.000 claims abstract description 31
- 238000005096 rolling process Methods 0.000 claims abstract description 14
- 238000004519 manufacturing process Methods 0.000 claims abstract description 6
- 230000009467 reduction Effects 0.000 claims description 12
- 229910000679 solder Inorganic materials 0.000 claims description 10
- FGUUSXIOTUKUDN-IBGZPJMESA-N C1(=CC=CC=C1)N1C2=C(NC([C@H](C1)NC=1OC(=NN=1)C1=CC=CC=C1)=O)C=CC=C2 Chemical compound C1(=CC=CC=C1)N1C2=C(NC([C@H](C1)NC=1OC(=NN=1)C1=CC=CC=C1)=O)C=CC=C2 FGUUSXIOTUKUDN-IBGZPJMESA-N 0.000 claims description 5
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 5
- 238000000137 annealing Methods 0.000 claims description 5
- 238000001816 cooling Methods 0.000 claims description 4
- 238000005097 cold rolling Methods 0.000 claims description 3
- 235000019587 texture Nutrition 0.000 description 30
- 238000006722 reduction reaction Methods 0.000 description 8
- 238000005476 soldering Methods 0.000 description 6
- 239000013078 crystal Substances 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 229910021419 crystalline silicon Inorganic materials 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 150000003376 silicon Chemical class 0.000 description 2
- 241000282337 Nasua nasua Species 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 150000001879 copper Chemical class 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000009975 flexible effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- LQBJWKCYZGMFEV-UHFFFAOYSA-N lead tin Chemical compound [Sn].[Pb] LQBJWKCYZGMFEV-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000001465 metallisation Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/042—PV modules or arrays of single PV cells
- H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys
- H01B1/026—Alloys based on copper
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/08—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of copper or alloys based thereon
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/042—PV modules or arrays of single PV cells
- H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
- H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
- H01L31/0512—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module made of a particular material or composition of materials
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
Abstract
The invention relates to an electrical conductor (2) having a longitudinal axis (A) parallel to the rolling direction of a conductor wire, comprising copper material and an attachment surface (7) configured for attaching to a receiving surface of a silicon wafer (3) to establish an electrical connection. The copper material has a pu rity of at least 99.5% wherein the grains have a cubic texture comprising a set of cubic axes directed within an up to 20 degree angular range to the longitudinal axis (A), and whereby at least 65% of the grains have said cubic texture. The invention also relates to a process for manufacturing conductor (2) and photovoltaic modules comprising said conductor (2), and silicon wafers.
Description
A N EW ELECTRICAL CONDUCTOR FOR ATTACHING SILICON WAFERS IN PHOTOVOLTAIC MODULES
THE FI ELD OF THE I NVENTION
The present invention refers to an elongated electrical conductor accordi ng to the characterized portion of claim 1 and a process for manufacturi ng an electrical conductor according the characterized portion of claim 10 as well as a photovoltaic module comprising said conductor attached to a silicon wafer. BACKGROUND OF THE I NVENTION AND PRIOR ART
A crystalline silicon photovoltaic module consists in general of a number of silicon wafers or solar cells connected in series. The series connection is made from the front of the first silicon wafer to the back of the next silicon wafer and so forth . The electrical connections between the silicon wafers are made by soldering two or three copper stri ng-wires on each side of the silicon wafers. There is a significant risk of bowing of the skin silicon wafers duri ng the solderi ng process or afterwards due to the fact that the string is stretched duri ng cooling . This happens because the coefficient of thermal expansion is significantly higher for copper than for silicon. The bowing is associated with tensile stresses in the thi n and brittle silicon wafer and results in a high frequency of cell breakage. Cracks may also be initiated at the edge of the wafers just under the string-wire due to the intense mechanical stress.
It is desired to reduce the thickness of the silicon wafers to reduce the electrical losses. Furthermore, traditional tin-lead sol- der is desired to be replaced with lead-free tin , which will result in increased soldering temperature. These factors act to i n-
crease the mechanical stress i n the silicon wafer. Moreover, at the same time, there is a need to maintai n the present wafer size, as well as the design of the metallisation pattern and the general concept of the stri ng-wires. Altogether, this means that the mechanical properties of the string-wire become a very important issue since they have a direct impact on the mechanical stress that arises in the silicon wafer during the soldering process. WO2009/049572 discloses an improved ca ble connection comprising an elastic design for an electrical conductor for silicon wafers i n plate-shaped solar modules. This design however does not solve the problem of breaking and cracking of the silicon wafers due to soldering .
US 7, 1 73, 188 descri bes an improved electrical conductor which is coated to prevent wrappi ng of the conductor during soldering . US2009/001 7325 descri bes rolled copper foil with improved flexi ble fatigue properties, which is made in a 5 step process resulting in copper with crystal grains having a cubic texture. This is however a material for use in high strength products.
There is still a need for improved copper material that can reduce the risk for fracture i n the silicon wafers. SUMMARY OF THE I NVENTION
The object of the present invention is to provide improved string- wires wherei n the stress in the copper material in the electrical conductor is minimised to prevent the load on the silicon wafers from becomi ng large enough to cause damage to the wafers.
The object is achieved by the electrical conductor initially defined characterized in that the copper material is present at a purity of at least 99.5% and wherein the grains have a cubic tex- ture comprising a set of cu bic axes directed withi n an u p to 20
degree angular range to the longitudinal axis, and whereby at least 65% of the grains have said cubic texture.
The advantage of this copper material is that it ensures that the stress in the copper string-wires is as minimised as possible so that the load on the silicon wafers is as small as possible. This stress level is determined by the mechanical properties of the string-wire, which are susceptible to control by tailoring the crystallographic texture and microstructure of the copper material.
The purity of the copper is important for the mechanical properties of the electrical conductor. In one embodiment the copper material has a purity of at least 99.9%. Beside the orientation of the grains in the cubic texture, it is also important that most of the copper material has the cubic texture. In one embodiment 70 to 100% of the grains have the cubic texture. To minimise the mechanical stress in the copper material, the orientation of the grains in the cubic texture is important. In another embodiment the set of cubic axes are directed within a 15 degree angular range to the longitudinal axis. In a further embodiment the the set of cubic axes are directed within a 10 de- gree angular range to the longitudinal axis.
The sharpness or strength of the copper texture is important with regard to the resulting anisotropy of mechanical properties. It is necessary that a sufficient proportions of grains (crystals) in the copper sheet/wire are correctly orientated with respect to the sheet axes. An important criterion in this regard is the degree of coincidence between the longitudinal axis of the string wire and the cube axes of the copper crystals. The cube axes are referred to as <100> directions in the standard crystallographic Miller index notation. Optimising the material requires a high degree of coincidence beween <100> directions in the grains
and the longitudinal axis of the sheet/wire. The texture strength is best described by a cube axis index (CA index), which is defined as the volume percentage of the copper that is orientated such that the angle between the longitudinal axis and <100> is less than 15 degrees. In one embodiment the cube axis index is at least 70%. For comparison, copper material having no specific texture (i.e. randomly orientated) may have a CA index below 15%. Preferably, the copper material is an Electrolytic Tough Pitch copper or an Oxygen-Free copper.
For a given level of (thermal) strain, the stress in the string-wire may depend on two factors, namely the elastic modulus (Young's modulus, E) and the yield stress (Rp) of the copper material. The Young modulus is controlled only by the crystallo- graphic texture, while the yield stress depends on both the texture and the microstructure (the grain structure). In one embodiment the copper material has a yield stress below 50 MPa.
A strong cubic texture may reduce the elastic stress level in the string-wire up to 45%, as compared to similar material without cubic texture. In one embodiment the copper material has a Young modulus below 95 GPa.
The object of the invention is also achieved by a process for manufacturing an electrical conductor comprising a copper material at a purity of at least 99.5% characterized in that the process comprises the steps of:
a) arranging the copper material to a rolling mill,
b) rolling the copper material along a rolling direction to a reduction from 20 to 80%, wherein a copper product is formed,
c) annealing the copper product at a temperature below 600°C,
d) optionally repeating steps b) and c),
e) cold rolling the copper product to a reduction of at least 80%, and
f) fin al a n n eal i n g the copper product at a temperatu re above 250°C.
As discussed above, the properties of the copper material are important to mi nimise the mechanical stress in the copper material . Therefore, i n one embodiment the process is preferably performed with copper material that has a purity of at least 99.9% . In another embodiment the grai n size of the copper material after steps b) and c) is from 5 to 25 μιτι. I n a further embodiment the copper material is an Electrolytic Tough Pitch copper or an Oxygen-Free copper. To optimise the mechan ical properties of the copper material obtained by the process descri bed above even further, some of the process parameters can be changed . I n another embodiment the reduction in step b) is from 30 to 80% . I n a further embodiment the temperature in step c) is from 300 to 400°C. I n yet an- other embodiment the reduction in step d ) is from 90 to 99%. I n one embodiment the temperature in step f) is above 500°C.
The object of the present invention is also achieved by an electrical conductor manufactured by the process descri bed above.
In one embodiment the attachment surface of the electrical conductor is coated with tin based solder material .
The invention further relates to a process for attachi ng the elec- trical conductor to a silicon wafer, characterized in that the attachment surface of the electrical conductor and the receiving surface of the silicon wafer are heated to melt the solder material , whereby an attachment is formed between the electrical conductor and the silicon wafer upon cooling of the heated ma- terial .
One embodiment of the invention relates to a photovoltaic module comprising at least one silicon wafer attached to at least one electrical conductor. BRI EF DESCRI PTI ON OF THE DRAWI NGS
The invention will now be explained more closely by means of a description of various embodiments and with reference to the drawings attached hereto.
Figure 1 . A schematic photovoltaic module comprising a series of silicon wafers connected by electrical conductors.
Figure 2. A schematic view of the receiving surface of a silicon wafer and the attachment surface of an electrical conductor.
Figure 3. A flow scheme of the manufacturing process.
DETAI LED DESCRI PTI ON OF VARIOUS EMBODI MENTS OF THE I NVENTI ON Fig . 1 shows an example of a photovoltaic module 1 containing at least one silicon wafer 3 attached to at least one electrical conductor 2. Normally, the photovoltaic module 1 comprises a series of silicon wafers 3 connected to each other by electrical conductors 2 , whereby one silicon wafer 3 is attached to at least two, or at least four electrical conductors 2.
Fig 2 shows the improved electrical conductor 2 for use in a photovoltaic module or crystalline silicon photovoltaic module 1 . The electrical conductor 2 comprises a conductor core 5 consist- ing of a copper material and a coati ng of tin based solder material 6. The coating preferably comprises a tin based lead-free solder material 6, but other solder material 6 may be used .
In general , the whole conductor core 5 of the electrical conduc- tor 2 is coated with the coating 6. For purpose of presenting the structure of the electrical conductor 2 , the conductor core 5 of a
right part of the electrical conductor 2 has been exposed in Fig 2. The conductor core 5 may have a rectangular cross-section. Through this rectangular cross-section the electrical conductor 2 forms a flat surface adapted to be attached to an upper and/or lower surfaces 4a, 4b of the silicon wafer 3.
The solder material 6 forms an attachment surface 7 adapted to be positioned in contact with the upper or lower surface 4a, 4b of the silicon wafer 3. Referri ng to fig . 1 , the attachment surface 7 is adapted to be positioned in contact with the receiving surface on the upper surface 4a of a first silicon wafer 3 (the electrical conductor 2 bei ng marked with a solid line) and with the receiving surface on the lower surface 4b of an adjacent second silicon wafer 3 (the electrical conductor 2 bei ng marked with a doted line). The upper surface 4a and the lower surface 4b are positioned on opposite sides of the first and second silicon wafer 3.
The electrical conductor 2 is attached to the silicon wafer 3 by positioning the conductor 2 in contact with the receiving surface on the upper surface 4a of the first silicon wafer 3 and the receiving surface on the lower surface 4b of the adjacent second silicon wafer 3, and heating the first and the second silicon wafer 3 together with the electrical conductor 2, thereby melting the solder material 6. Hereby, an attachment is formed between the electrical conductor 2 and the silicon wafers 3 upon cooling of the heated material .
Because of the heat used duri ng soldering and because the sili- con wafers 3 are fragile, it is important to use a conductor core 5 material of the electrical conductor 2 that prevents damaging the silicon wafer 3.
A low yield strength of the conductor core 5 material in the di- rection of a longitudinal axis A of the conductor core 5 is desired in order to mitigate the mechanical stress i n the silicon wafers 3.
Such stesses occur due to difference in thermal conductivity between the material of the silicon wafers 3 and the material of the electrical conductor 2. The cond uctor core 5 comprises of copper material that has a purity of at least 99.5%. The purity may also be 99,6%, or 99,7%, or 99,8% , or 99,9%. The amount of impurities in the copper material is preferably less than 0.5% . The copper material may be any copper material available on the market. Preferably, the copper material is an Electrolytic Tough Pitch copper or an Oxygen-Free copper.
The mechanical properties improve by the number of grains that have the cubic texture. Preferably, at least 70% , or 75% of the grains in the copper material of the electrical conductor have the cubic texture. The copper material may have from 80 to 100% , or 80 to 90%, or 90 to 99.9% , or 95 to 99.9% of the grains in the cubic texture.
The longitudi nal axis A of the conductor core 5 is essentially parallel to the rolling direction of a conductor wire. Furthermore, the copper material of the conductor core 5 comprises of grai ns which are orientated in a cubic texture comprising a first set of cu bic axes directed to the long itudinal axis A and other sets of cubic axes that are directed essentially perpendicular to the longitudinal axis A. The angle of the first set of axes may deviate from the longitudinal axis A. This symmetrical deviation is pefe- ably less than ± 30 degrees relative to the longitudinal axis A. The first set of cubic axes may be directed within a range up to 25 degrees to the longitudinal axis A. This set of cubic axes may also be directed within a range up to 20, or up to 15, or up to 10, or up to 5 degrees to the longitudinal axis A.
For the sake of clarity, the electrical conductor 2 of the present invention may comprise any combination of ranges and i ntervals
mentioned above for any of the purity of the copper material , range of degrees to the longitudi nal axis A and amount of grai ns that have the cubic texture. For example, the copper material may comprise of 99.95% pure copper, a set of cubic axes di- rected withi n the range up to 12 degrees to the longitudinal axis A and from 80 to 100% of the grains in the cubic texture or any other value that falls within the ranges and intervals mentioned above. Assessment of the texture of the copper material in the stri ng- wire of the electrical conductor 2 can be made using conventional techniques such as X-ray diffraction and electron back- scatteri ng diffraction (EBSD). The mechanical properties of the material that can be measured are for example the yield stress or strength and the Young modulus. The Taylor factor may be evaluated from measurements of the texture.
The electrical conductor 2 of the present invention preferably comprises copper material that has a yield stress below 50, or 45, or 40 MPa. The yield stress in the stri ng-wire of the electrical conductor 2 is preferably reduced by at least 1 0%, or 20%, or 30%, or more as compared to similar material without cubic texture. The Young modulus is preferably below 95, or 80, or 70 GPa.
The cubic orientation also conveys advantages in reduci ng the yield stress of the string-wire. A strong cubic texture may reduce the yield stress level in the string-wire by 20%, or 40%, or more as compared to similar material without cubic texture. This can be definied i n terms of the so called Taylor factor (M) for plastic flow. M is lower for metals that have a cubic texture compared to metals without the cubic texture. I n another embodiment the copper material has a Taylor factor of 3, or below 2,75, or less. The copper material comprised in the electrical conductor 2 may be manufactured using different processes. However, control of
material and process pa rameters a re i m porta nt to o btai n the preferred strong cu bic texture.
The copper material used in the process preferably has a purity of at least 99.5%. The purity may also be at least 99,6%, or 99,7%, or 99,8% , or 99,9%. The amount of impurities in the copper material is preferably less than 0.5% .
The copper material used in the process descri bed above is may be Electrolytic Tough Pitch copper or Oxygen-Free copper.
Fig 3 shows a flow chart for the manufacturing process. The process starts by arrangi ng the copper material to a rolling mill in step a). Next, in step b), the copper material is rolled along a rolling direction to reduce the copper material to form a product such as for example a strip, a sheet or a flat wire. This reduction may be from 20 to 90%, or 20 to 80%, or 20 to 70%, or 30 to 90%, or 30 to 80%, or 30 to 70%. The rolling i n step b) may be performed cold or hot or at an intermediate cold temperature up to 150°C, preferably at a temperature below 1 25°C, or 100°C, or 75°C. I n step c) the copper product is annealed at a temperature below 600°C , or 500°C, or 400°C. The temperatu re may be i n the range from 300 to 400°C. I n one em bodi ment the temperature is 350°C.
The microstructure of the copper is prefera bly a fi ne g rain size whereby the grain size after steps b) and c) does not exceed 30 μιτι. Preferably, the grain size is below 25 μιτι, or 20 μιτι, or 1 5 μιτι or from 2 to 25 μιτι, or 5 to 20 μιτι, or 5 to 15 μιτι, or 2 to 10 μιη. Steps b) and c) may be repeated one, two, or more times if necessary.
Annealing step c) is followed by cold rolling the product in step e) to reduce the product at least 80%, or 90%, or 95%, or 98%, or from 90 to 99% , or 95 to 99%, or 98 to 99% . Final annealing
of the product is done i n step f). The temperatu re i n step f) is preferably above 250°C, or 400°C, or 500°C, or 600°C.
The cubic texture in the copper material obtained by the process descri bed a bove is orientated such that the fi rst set of cu bic axes are directed essentially to the rolling direction of the copper product as used in the manufacturing process of the product (i .e. the longitudi nal axis A). The other sets of cubic axes are directed essentially perpendicular to the rolling direction of the copper product.
For the sake of clarity, the process may be conducted with any combination of ranges and intervals mentioned above for any of the pu rity of the copper material , g rai n size , temperatu re and red uctions . For example , the process may be cond ucted with copper material comprising 99.9% pure copper, with a reduction in step b) from 30 to 80% at an intermediate level of cold (below 150°C), the annealing step c) may be done at 350°C, resulting in a grain size below 26 μιτι and the reduction in step d ) may be in the range from 90 to 98%, and the temperature in step f) may be above 500°C.
The terms 'essentially' as used herein shall be interpreted in the broadest sense, i ncluding all or almost all , or 99%, 95%, 90%, 85%, 80%, or 75% of all .
The present invention is not limited to the embodiments disclosed but may be varied and modified withi n the scope of the following claims.
Claims
Claims
An elongated electrical conductor (2) having a longitudinal axis (A) essentially parallel to the rolling direction of a conductor wire, which conductor (2) comprises of copper material, an attachment surface (7) configured to be attached to a receiving surface of a silicon wafer (3) to establish an electrical connection between the silicon wafer (3) and the electrical conductor (2), characterized in that the copper material is present at a purity of at least 99.5%, and wherein the grains have a cubic texture comprising a set of cubic axes directed within an up to 20 degree angular range to the longitudinal axis (A), and whereby at least 65% of the grains have said cubic texture.
The electrical conductor (2) according to claim 1, characterized in that the copper material has a purity of at least 99.9%.
The electrical conductor (2) according to claims 1 or 2, characterized in that 70 to 100% of the grains have the cubic texture.
The electrical conductor (2) according to any one of claims 1 to 3, characterized in that the set of cubic axes are directed within a 15 degree angular range to the longitudinal axis (A).
The electrical conductor (2) according to any one of claims 1 to 3, characterized in that the set of cubic axes are directed within a 10 degree angular range to the longitudinal axis (A).
6. The electrical conductor (2) according to any one of claims 1 or 5, characterized in that the cube axis index is at least 70%.
The electrical conductor (2) according to any one of claims 1 or 6, characterized in that the copper material is an Electrolytic Tough Pitch copper or an Oxygen-Free copper.
The electrical conductor (2) according to any one of claims 1 or 7, characterized in that the copper material has a yield stress below 50 MPa.
The electrical conductor (2) according to any one of claims 1 or 8, characterized in that the copper material has a Young modul us below 95 GPa.
10. A process for the manufacturing of an electrical cond uctor (2) , comprisi ng a copper material at a pu rity of at least 99.5%, characterized in that the process comprises the steps of:
a) arranging the copper material to a rolling mill ,
b) rolling the copper material along a rolling direction to a reduction from 20 to 80%, wherei n a copper product is formed ,
c) annealing the copper product at a temperatu re below 600°C,
d) optionally repeating the steps b) and c),
e) cold rolling the copper product to a reduction of at least 80%, and
f) fin al a n n eal i n g the copper product at a temperatu re above 250°C.
1 1 . The process according to claim 10, characterized in that the copper material has a purity of at least 99.9%.
12. The process according to claims 10 and 11, characterized in that the grain size after steps b) and c) is 5 to 25 μιη. 13. The process according to any one of claims 10 or 12, characterized in that the copper material is an Electrolytic Tough Pitch copper or an Oxygen-Free copper.
14. The process according to any one of claims 10 or 13, characterized in that the reduction in step b) is from 30 to
80%.
15. The process according to any one of claims 10 or 14, characterized in that the temperature in step c) is from 300 to 400°C.
16. The process according to any one of claims 10 or 15, characterized in that the reduction in step d) is from 90 to 99%.
17. The process according to any one of claims 10 or 16, characterized in that the temperature in step f) is above 500°C. 18. An electrical conductor (2) manufactured by the process according to any one of claims 10 to 17.
19. The electrical conductor (2) according to any one of claims 1 to 9 or 18, characterized in that the attachment surface (7) is coated with tin based solder material (6).
20. A process for attaching the electrical conductor (2) according to claim 19 to a silicon wafer (3), characterized in that the attachment surface (7) of the electrical conduc- tor (2) and the receiving surface of the silicon wafer (3) are heated to melt the solder material (6), whereby an attach-
ment is formed between the electrical conductor (2) and the silicon wafer (3) upon cooling of the heated material.
21. A photovoltaic module (1) comprising at least one silicon wafer (3) attached to at least one electrical conductor (2) according to claim 19.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/EP2010/068496 WO2012072109A1 (en) | 2010-11-30 | 2010-11-30 | A new electrical conductor for attaching silicon wafers in photovoltaic modules |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP2647059A1 true EP2647059A1 (en) | 2013-10-09 |
Family
ID=44454104
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP10782319.7A Withdrawn EP2647059A1 (en) | 2010-11-30 | 2010-11-30 | A new electrical conductor for attaching silicon wafers in photovoltaic modules |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US20130247979A1 (en) |
| EP (1) | EP2647059A1 (en) |
| JP (1) | JP2014509444A (en) |
| KR (1) | KR20140043701A (en) |
| CN (1) | CN103384921A (en) |
| AU (1) | AU2010364692A1 (en) |
| MX (1) | MX2013005983A (en) |
| SG (1) | SG190212A1 (en) |
| WO (1) | WO2012072109A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111406297B (en) | 2018-01-10 | 2021-10-22 | 埃赛克斯古河电磁线日本有限公司 | Insulated wire |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3009383B2 (en) * | 1998-03-31 | 2000-02-14 | 日鉱金属株式会社 | Rolled copper foil and method for producing the same |
| JP4329532B2 (en) | 2003-07-15 | 2009-09-09 | 日立電線株式会社 | Flat conductor, method for manufacturing the same, and lead wire |
| JP4162087B2 (en) * | 2003-08-22 | 2008-10-08 | 日鉱金属株式会社 | Highly flexible rolled copper foil and method for producing the same |
| CN101504956B (en) * | 2003-11-27 | 2012-01-11 | 京瓷株式会社 | Solar cell module |
| JP4662834B2 (en) * | 2005-10-12 | 2011-03-30 | Ｊｘ日鉱日石金属株式会社 | Copper or copper alloy foil for circuit |
| JP2008182171A (en) * | 2006-12-28 | 2008-08-07 | Hitachi Cable Ltd | Solder-plated wire for solar cell and manufacturing method thereof, and solar cell |
| JP2008248274A (en) * | 2007-03-29 | 2008-10-16 | Nikko Kinzoku Kk | Rolled copper foil |
| JP4466688B2 (en) | 2007-07-11 | 2010-05-26 | 日立電線株式会社 | Rolled copper foil |
| JP4721067B2 (en) * | 2007-07-12 | 2011-07-13 | 日立電線株式会社 | Manufacturing method of copper alloy material for electric and electronic parts |
| WO2009049572A1 (en) * | 2007-10-19 | 2009-04-23 | Solarwatt Ag | Cable connector for solar cells of plate-shaped solar modules |
| US20090173414A1 (en) * | 2008-01-08 | 2009-07-09 | Takemi Muroga | Rolled Copper Foil and Manufacturing Method of Rolled Copper Foil |
| CN106098829A (en) * | 2008-11-27 | 2016-11-09 | 日立金属株式会社 | Wire used for solar batteries and the manufacture method of solaode |
| CN103080347A (en) * | 2010-08-27 | 2013-05-01 | 古河电气工业株式会社 | Copper alloy sheet and method for producing same |
-
2010
- 2010-11-30 MX MX2013005983A patent/MX2013005983A/en not_active Application Discontinuation
- 2010-11-30 JP JP2013541214A patent/JP2014509444A/en active Pending
- 2010-11-30 CN CN2010800702945A patent/CN103384921A/en active Pending
- 2010-11-30 SG SG2013035506A patent/SG190212A1/en unknown
- 2010-11-30 AU AU2010364692A patent/AU2010364692A1/en not_active Abandoned
- 2010-11-30 WO PCT/EP2010/068496 patent/WO2012072109A1/en active Application Filing
- 2010-11-30 EP EP10782319.7A patent/EP2647059A1/en not_active Withdrawn
- 2010-11-30 US US13/990,478 patent/US20130247979A1/en not_active Abandoned
- 2010-11-30 KR KR1020137016739A patent/KR20140043701A/en not_active Application Discontinuation
Non-Patent Citations (1)
| Title |
|---|
| See references of WO2012072109A1 * |
Also Published As
| Publication number | Publication date |
|---|---|
| KR20140043701A (en) | 2014-04-10 |
| MX2013005983A (en) | 2013-12-06 |
| SG190212A1 (en) | 2013-06-28 |
| AU2010364692A1 (en) | 2013-05-30 |
| JP2014509444A (en) | 2014-04-17 |
| US20130247979A1 (en) | 2013-09-26 |
| WO2012072109A1 (en) | 2012-06-07 |
| CN103384921A (en) | 2013-11-06 |
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